Hall sensor devices are semiconductor devices used to a measure magnetic field. They produce an output signal proportional to the magnetic field. At zero magnetic field, they tend to output a signal, which is usually different from zero: this is their offset error (i.e., zero field error).
Hall sensor devices comprise a Hall effect region where the Hall effect takes place and three or more contacts in or in ohmic contact with the Hall effect region. A contact may be understood as a contact tub located in or in touch with the Hall effect region. An electrical contact to the Hall sensor region may be made by a contact diffusion or implantation process, for example. Sometimes several contacts can be connected via metal lines (in the interconnect layer of the semiconductor technology) to the same terminal. Terminals can be used to supply the device with electric power and to tap its output signals.
Hall plates, which are also known as Horizontal Hall sensor devices or HHalls, are flat devices with thicknesses 5 to infinitely (typically 50) times smaller than their lateral size. They are used to detect magnetic field components along their thickness direction (i.e. the direction into the semiconductor substrate). In silicon technology, Hall plates are currently typically 1 to 3 μm thick and 10 to 100 μm large in lateral directions. Their layout can be rectangular, square, circular, octagonal, cross-shaped, or even triangular.
Vertical Hall sensor devices or VHalls are stout devices where one lateral dimension is comparable (0.2 times up to 10 times) to their thickness direction (i.e. direction into the semiconductor substrate). They often have the shape of long stripes, mostly straight, sometimes curved, arc-shaped, or even circular rings. They can be used to detect magnetic field components parallel to the semiconductor main surface.
The terms “horizontal” and “vertical” denote the orientation of the plate-like geometry of the devices with respect to the main surface of the semiconductor die.
One approach for reducing or eliminating offset error is using a multi-contact Hall sensor. Three-contact or four-contact HHalls or VHalls may be operated in a spinning current-type mode, which changes the supply or sense role of the contacts in multiple clock phases such that any offset is reduced when the signals from the multiple clock phases are combined. The residual offset generally depends on the supply voltage, at which the device is operated: with larger supply voltage the residual offset grows. This is caused by self-heating and electrical non-linearities of the devices, which are larger at larger supply voltages. In order to achieve low residual offset the devices need to be operated at low supply voltage of e.g., 0.5V (instead of larger supply voltages of 2 to 3V). Even so, the residual offset error can remain higher than desired, such as in the range of about 1 milli-Tesla (mT).
Hence, there may be a desire for operating Hall sensor devices with reduced residual offset error.